They could. They could do a lot of things, but ultimately “they” will be the Secret Service who will make the decision and that decision will come down to what’s best for national security, what’s best for the former Presidents protection, what’s best for the protection of its agents and their ability to execute their mission, and what resources and funds are available to them for all of the above.
I do agree with you that the gag order might be the best possible chance of seeing Trump in jail. It’s quite possible the Secret Service might entertain a night in jail since that would be relatively easy to accomplish if it were prepared for. There’s no doubt the Secret Service have requested advance notice from the court.
To put that in perspective, the last time the Obamas went out for dinner, it took the Secret Service two weeks to prepare and they had to kick some restaurant employees out that evening due to infractions as petty as shop lifting.
Prison time however, I just don’t see it happening and honestly would rather see the amount of tax dollars that would take spent elsewhere.